Ventilation duct insert



FIG. 1 is a perspective view of a ventilation duct insert, with the flaps closed;

FIG. 2 is a top view of the ventilation duct insert of FIG. 1, with the flaps closed;

FIG. 3 is a bottom view of the ventilation duct insert of FIG. 1, with the flaps closed;

FIG. 4 is a left side view of the ventilation duct insert shown in FIG. 1;

FIG. 5 is a right side view of the ventilation duct insert shown in FIG. 1;

FIG. 6 is a front side view of the ventilation duct insert shown in FIG. 1;

FIG. 7 is a rear side view of the ventilation duct insert shown in FIG. 1;

FIG. 8 is a cross-sectional view through line 8-8 of the ventilation duct insert shown in FIG. 2;

FIG. 9 is a cross-sectional view through line 9-9 of the ventilation duct insert shown in FIG. 2;

FIG. 10 is a front perspective view of the ventilation duct insert of FIG. 1, with one flap open; and,

FIG. 11 is a front perspective view of the ventilation duct insert as shown in FIG. 1, with all flaps open. 

CLAIM The ornamental design for a ventilation duct insert, as shown and described. 